Scorpionate-Type Coordination in MFU-4lMetal-Organic Frameworks: Small-Molecule Binding and Activation upon the Thermally Activated Formation of Open Metal Sites

Inhibition, Binding of Organometallics, and Thermally Induced CO Release in an MFU-4-Type Metal-Organic Framework Scaffold with Open Bidentate Bibenzimidazole Coordination Sites

Triazolate-based MFU-4-type metal-organic frameworks are promising candidates for various applications, of which heterogeneous catalysis has emerged as a hot topic owing to the facile post-synthetic metal and ligand exchange in Kuratowski secondary building units (SBUs). Herein, we present the largest non-interpenetrated isoreticular MFU-4-type framework CFA-19 ([Co₅^IICl₄(H₂-bibt)₃]; H₄-bibt = 1,1',5,5'-tetrahydro-6,6'-biimidazo[4,5-f]benzotriazole; CFA-19 = Coordination Framework Augsburg University-19) and the CFA-19-Tp derivative featuring trispyrazolylborate inhibited SBUs as a scaffold with open bibenzimidazole coordination sites at the backbone of the H₄-bibt linker. The proof-of-principle incorporation of accessible M^IBr(CO)₃ (M = Re, Mn) sites in CFA-19-Tp was revealed by single-crystal X-ray diffraction, and a thermally induced CO release was observed for MnBr(CO)₃. Deprotonation of bibenzimidazole was also achieved by the reaction with ZnEt₂.

A Theoretical Investigation of Cu+, Ni2+ and Co2+-exchanged Zeolites for Hydrogen Storage

This study investigates the H 2 adsorption on Cu + , Ni 2+ and Co 2+ -exchanged SSZ-13 (CHA) and SSZ-39 (AEI) using periodic DFT computations. Most stable Cu + position was found to be the 6-membered-ring window for both zeolites. Similarly, for investigated Ni 2+ and Co 2+ loadings on 6-membered-ring windows, the third nearest neighbor Al positions, i.e., Al-O-Si-O-Si-O-Al coordination, was found to be the most stable position. H 2 adsorption was investigated for all the Cu + , Ni 2+ and Co 2+ centers. AEI and CHA resulted in similar H 2 -Cu interactions for the Al and B substituted structures. H 2 adsorption on Cu + located in the 8-membered-ring gave the highest adsorption energy for both frameworks. Replacing Al with B in the framework increased the electron back donation from Cu + (3d) orbitals to H 2 antibonding orbital (s H2 * ). The H 2 adsorption energies on the Ni 2+ and Co 2+ -exchanged zeolites were found to be between -15 and -44 kJ/mol. Higher energy values were observed on the AEI framework, especially when two Al atoms have the Al-O-Si-O-Al configuration. Lesser interaction of the d-orbitals in the case of the Co 2+ and Ni 2+ cations resulted in heat of H 2 adsorption close to optimum values required for H 2 storage on porous materials.

CFA-18: a homochiral metal-organic framework (MOF) constructed from rigid enantiopure bistriazolate linker molecules

In this work, we introduce the first enantiopure bistriazolate-based metal-organic framework, CFA-18 (Coordination Framework Augsburg-18), built from the R-enantiomer of 7,7,7',7'-tetramethyl-6,6',7,7'-tetrahydro-3H,3'H-5,5'-spirobi[indeno[5,6-d]-[1,2,3]triazole] (H2-spirta). The enantiopurity and absolute configuration of the new linker were confirmed by several chiroselective methods. Reacting H2-spirta in hot N,N-dimethylformamide (DMF) with manganese(ii) chloride gave CFA-18 as colorless crystals. The crystal structure with the composition [Mn2Cl2(spirta)(DMF)2] was solved using synchrotron single-crystal X-ray diffraction. CFA-18 shows a framework topology that is closely related to previously reported metal-azolate framework (MAF) structures in which the octahedrally coordinated manganese(ii) ions are triazolate moieties, and the chloride anions form crosslinked one-dimensional helical chains, giving rise to hexagonal channels. In contrast to MAFs crystallizing in the centrosymmetric space group R3[combining macron], the handedness of the helices found in CFA-18 is strictly uniform, leading to a homochiral framework that crystallizes in the trigonal crystal system within the chiral space group P3121 (no. 152).

Metal-Organic Frameworks for Hydrogen Energy Applications: Advances and Challenges

Hydrogen is in limelight as an environmental benign alternative to fossil fuels from few decades. To bring the concept of hydrogen economy from academic labs to real world certain challenges need to be addressed in the areas of hydrogen production, storage, and its use in fuel cells. Crystalline metal-organic frameworks (MOFs) with unprecedented surface areas are considered as potential materials for addressing the challenges in each of these three areas. MOFs combine the diverse chemistry of molecular linkers with their ability to coordinate to metal ions and clusters. The unabated flurry of research using MOFs in the context of hydrogen energy related activities in the past decade demonstrates the versatility of this class of materials. In the present review, we discuss major strategical advances that have taken place in the field of "hydrogen economy and MOFs" and point out issues requiring further attention.

Formation of a quasi-solid structure by intercalated noble gas atoms in pores of CuI-MFU-4l metal–organic framework

Ten crystallographically different positions for Xe and eight positions for Kr form a quasi-solid structures within the large-pore metal–organic framework Cu^I-MFU-4l.